The preparation and use of 2-amino-5-halo-6-alkyl-4-pyrimidinols as antiviral agents is known (U.S. Pat No. 3,956,302 and Nichols, Weed and Underwood, Antimicrobial Agents and Chemotherapy 9,433, 1976). Preparation of 2-amino-5-bromo-6-phenyl-4-pyrimidinol (V, where X.sub.3 is Br and X.sub.1 is phenyl) has been reported (Brown and Stevens, JCS Perkin I, 1023, 1975) but no utility has been described for this material. Snell, Elias and Freeman in G.B. 1,223,686 (1967) disclose a variety of 5,6-disubstituted 2-amino-4-pyrimidinols, such as 2-dimethylamino-5-bromo-6-methyl-4-pyrimidinol. Various 5-unsubstituted 2-amino-6-arylpyrimidinols are known (e.g., Shirahawa, Yakuyaku Fasshi 50, 1562, 1960 (CA 55, 10651b); Kulkarui et al., J. Sci. and Ind. Res. Indil. 19C, 6, 1960; and U.S. Pat. No. 2,776,283. Diuretics and cardioregulatory properties are described for various 2-amino and 2-substituted amino-5-aminomethyl and 5-aryl- 6-aryl-4-pyrimidinols, U.S. Pat. No. 2,704,285, U.S. Pat. No. 2,723,777 and U.S. Pat. No. 2,776,283.
The 2-amino-6-aryl-5-substituted pyrimidinols of this invention have been shown to exhibit antiviral activity, an improved therapeutic ratio and fewer side effects and are useful in preventing and treating viral infections. The antiviral activity of many of the compounds is associated with increased production of interferon. Other compounds exhibit antiviral activity but do not induce interferon production.
The 2-amino-6-aryl-5-substituted pyrimidinols of this invention exhibit immunoregulatory activity of the following types: increased antibody formation, increase in natural killer cells, activation of macrophages, increase in hematopoietic stem cells and decrease in generation of allospecific killer cells.